Golf ball

Abstract

An object of the present invention is to provide a golf ball showing a low spin rate on driver shots and a high spin rate on approach shots. The present invention provides a golf ball comprising a spherical center, at least two envelope layers covering the spherical center, and a cover covering the envelope layers, wherein an envelope layer (Es1) formed from a material having a lowest material hardness among a center constituent material and envelope layers constituent materials, is disposed in a region located at a distance from 36.0% to 65.0% of a golf ball radius from a center point of the golf ball.

The invention claimed is: 
     
       1. A golf ball comprising a spherical center, at least four envelope layers covering the spherical center, and a cover covering the envelope layers,
 wherein an envelope layer (Es 1 ), which is formed from a material having a material hardness (Hs 1 ) that is lowest among the center and other envelope layers, is disposed in a region located at a radial distance of from 36.0% to 65.0% of the golf ball radius from the golf ball center point, 
 an envelope layer (Eh 1 ), which is formed from a material having a material hardness (Hh 1 ) that is highest among the center, cover and other envelope layers, is disposed in a region located at a radial distance of from 85.0% to 99.5% of the golf ball radius from the golf ball center point, 
 an envelope layer (E 11 ) is disposed between the spherical center and the envelope layer (Es 1 ), and 
 a material hardness (H 11 ) of the envelope layer (E 11 ) is higher than the material hardness (Hs 1 ) of the envelope layer (Es 1 ) and smaller than a material hardness (Ho 1 ) of the spherical center. 
 
     
     
       2. The golf ball according to  claim 1 , wherein the envelope layer (Es 1 ) is disposed in a region located at a radial distance of from 40.0% to 62.5% of the golf ball radius from the golf ball center point. 
     
     
       3. The golf ball according to  claim 1 , wherein a hardness difference (Hh 1 −Hs 1 ) between the material hardness (Hs 1 ) of the envelope layer (Es 1 ) and the material hardness (Hh 1 ) of the envelope layer (Eh 1 ) is 30 or more in Shore D hardness. 
     
     
       4. The golf ball according to  claim 1 , wherein a hardness difference (Ho 1 −Hs 1 ) between the material hardness (Hs 1 ) of the envelope layer (Es 1 ) and the material hardness (Ho 1 ) of the spherical center is 1 or more in Shore D hardness. 
     
     
       5. The golf ball according to  claim 1 , wherein the envelope layer (Es 1 ) has the material hardness (Hs 1 ) of 30 or less in Shore D hardness. 
     
     
       6. The golf ball according to  claim 1 , wherein a hardness difference (Hh 1 −Ho 1 ) between the material hardness (Hh 1 ) of the envelope layer (Eh 1 ) and the material hardness (Ho 1 ) of the spherical center is 1 or more in Shore D hardness. 
     
     
       7. The golf ball according to  claim 1 , wherein the envelope layer (Eh 1 ) has the material hardness (Hh 1 ) of 30 or more in Shore D hardness. 
     
     
       8. The golf ball according to  claim 3 , wherein a hardness difference (Ho 1 −Hs 1 ) between the material hardness (Hs 1 ) of the envelope layer (Es 1 ) and the material hardness (Ho 1 ) of the spherical center is 1 or more in Shore D hardness, and a hardness difference (Hh 1 −Ho 1 ) between the material hardness (Hh 1 ) of the envelope layer (Eh 1 ) and the material hardness (Ho 1 ) of the spherical center is 1 or more in Shore D hardness. 
     
     
       9. The golf ball according to  claim 8 , wherein the envelope layer (Es 1 ) has the material hardness (Hs 1 ) of 30 or less in Shore D hardness, and the envelope layer (Eh 1 ) has the material hardness (Hh 1 ) of 30 or more in Shore D hardness. 
     
     
       10. The golf ball according to  claim 1 , wherein the spherical center has the material hardness (Ho 1 ) in a range from 15 to 55 in Shore D hardness. 
     
     
       11. The golf ball according to  claim 1 , wherein
 the golf ball has a diameter ranging from 40 mm to 45 mm, 
 the diameter of the spherical center is 20 mm or less, 
 the thickness of the envelope layer (Eh 1 ) is 3 mm or less, and 
 the thickness of the cover is 1.0 mm or less. 
 
     
     
       12. The golf ball according to  claim 1 , wherein the hardness (Shore D hardness) ratio (Hh 1 /Hs 1 ) between the material hardness (Hs 1 ) of the envelope layer (Es 1 ) and the material hardness (Hh 1 ) of the envelope layer (Eh 1 ) ranges from 1.1 to 35. 
     
     
       13. The golf ball according to  claim 1 , wherein the hardness (Shore D hardness) ratio (Ho 1 /Hs 1 ) between the material hardness (Hs 1 ) of the envelope layer (Es 1 ) and the material hardness (Ho 1 ) of the center ranges from 1.05 to 20. 
     
     
       14. The golf ball according to  claim 1 , wherein the hardness (Shore D hardness) ratio (Hh 1 /Ho 1 ) between the material hardness (Hh 1 ) of the envelope layer (Eh 1 ) and the material hardness (Ho 1 ) of the center ranges from 1.0 to 2.4. 
     
     
       15. The golf ball according to  claim 1 , wherein
 the spherical center has a diameter in a range from 5 mm to 25 mm, and 
 the compression deformation amount (deformation amount of the center along the compression direction) of the spherical center when applying a load from 98 N as an initial load to 1275 N as a final load to the spherical center ranges from 1.5 mm to 5.0 mm. 
 
     
     
       16. The golf ball according to  claim 1 , wherein the thickness of the envelope layer other than the envelope layer (Es 1 ) and the envelope layer (Eh 1 ) ranges from 0.1 mm to 15 mm. 
     
     
       17. The golf ball according to  claim 1 , wherein a material hardness (Hc 1 ) of the cover ranges from 5 to 55 in Shore D hardness. 
     
     
       18. The golf ball according to  claim 1 , wherein
 the golf ball has a diameter in a range from 40 mm to 45 mm, and 
 the compression deformation amount (deformation amount along the compression direction) of the golf ball when applying a load from 98 N as an initial load to 1275 N as a final load to the golf ball ranges from 2.0 mm to 4.0 mm.